1. Field of the Invention
The invention relates to a method of manufacturing a matrix device, and more particularly, to a method of manufacturing a thin film transistor liquid crystal display (TFT-LCD).
2. Description of the Prior Art
Since the progress of science and technology has led to small, effective, and portable intelligent information products, display devices have played an important role in modern society. In recent years, display devices have undergone great improvements in the areas of high performance quality, larger size, and lower cost. TFT-LCDs have characteristics of thinness, lightness and low power consumption and are expected to have in future a large market as a display device to replace CRTs. It is an important subject to develop a fabrication technique for realizing high achievement and low prices of TFT-LCDs.
Either for a conventional twist nematic (TN) LCD or for a recently developed wide view angle LCD, such as the IPS-LCD and the MVA-LCD, switch devices are required to control changes of the images. A popularly used switch device, TFT, includes a gate electrode, a source electrode, a drain electrode, and other needed semiconductor or insulating layers. The fabrication process of a TFT substantially decides the total process steps of a whole LCD, so simplifying the fabrication process of the TFT can realize low prices of TFT-LCDs.
The conventional fabrication method utilizes 5 or 4 masks to achieve a TFT in a liquid crystal display. The necessary elements of a TFT device include a source electrode, a drain electrode, a gate electrode and a channel region. For forming these necessary elements, the regular process steps are required and thus difficult to be omitted. However, with the application of halftone photolithograph making progress, the photo-etching-process can use a single mask to form photoresistors into different thicknesses. This makes reduction of the fabrication process possible.